Fosi Audio DS2 Portable DAC & Amp Review

[Eddie]

You understand incorrectly. It's the DS2's hardware fading that comes into play when exclusive mode is enabled — not foobar2000's. I have disabled fading altogether in foobar2000.

Now I'm even more confused...
So my understanding is this:
• on Windows 11 you use DS2 with foobar2000 in WASAPI exclusive mode
• your source is PCM (with e.g. 24 bits/96 kHz), but not DSD
• when you start or stop a track => no fades (and no pops and no clicks)
• when you seek within a track => fades
Please correct me if I'm wrong. I ordered the DS2 from Amazon and would cancel it if there was any hardware fading.

 

[alexanderino]

Now I'm even more confused...
So my understanding is this:
• on Windows 11 you use DS2 with foobar2000 in WASAPI exclusive mode
• your source is PCM (with e.g. 24 bits/96 kHz), but not DSD
• when you start or stop a track => no fades (and no pops and no clicks)
• when you seek within a track => fades
Please correct me if I'm wrong. I ordered the DS2 from Amazon and would cancel it if there was any hardware fading.

When I start/un-pause/stop after a few seconds, there is a fade-in/fade-out. Other than that, correct.

I hope the DS2 is firmware-upgradeable.

 

[Eddie]

When I start/stop after a few seconds, there is a fade-in/fade-out.

Oh no, such behavior is exactly what I definitely don't want. Very unfortunate.
Nevertheless, thanks for your information.

 

[Labjr]

If it's fading in/out doesn't that mean it's not playing bit perfect or native DSD?

 

[Eddie]

If it's fading in/out doesn't that mean it's not playing bit perfect...

Yes, that's exactly my point. It obviously alters audio when fading. It's not bit-perfect.
WASAPI exclusive mode is Windows' built-in alternative to ASIO. It can be bit-perfect if implemented correctly by the hardware. Just like ASIO.
I guess the USB bridge Savitech SA9312 is responsible for this behavior, whether silicon or firmware.
Maybe it's intended as a feature, but for me, it's really a very annoying bug.

 

[GeekyBastard]

Maybe it's intended as a feature, but for me, it's really a very annoying bug.

It's not fading, but muting for around 1/2~1 second to avoid pop sound during sample rate or PCM/DSD format changing, if there's no change, there's no muting, so it is a feature, and basically every dac dongle on the market does that, because most consumers will complain if there's a pop sound, it's actually a desired feature for most people.

 

[Labjr]

It's not fading, but muting for around 1/2 second to avoid pop sound during sample rate or PCM/DSD format changing, if there's no change, there's no muting, so it is a feature, and basically every dac dongle on the market does that, because most consumers will complain if there's a pop sound, it's actually a desired feature for most people.

So it's fine with gapless playback?

 

[amirm]

If you ever get the chance, could you do the power versus distortion charts with the noise level corrected?

Unfortunately I don't have a way to do that. The ASIO emulation adds that noise in this class of device and I need to use it to perform sweeps.

 

[staticV3]

Unfortunately I don't have a way to do that. The ASIO emulation adds that noise in this class of device and I need to use it to perform sweeps.

Out of curiosity, did you give FlexASIO a try?

GitHub - dechamps/FlexASIO: A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME.

A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME. - dechamps/FlexASIO

github.com

GitHub - flipswitchingmonkey/FlexASIO_GUI: Simple configuration GUI for FlexASIO

Simple configuration GUI for FlexASIO. Contribute to flipswitchingmonkey/FlexASIO_GUI development by creating an account on GitHub.

github.com

It's a more configurable version of ASIO4All basically, and when configured to use WMD-KS internally, has served me very well WRT stability and transparency.

 

[alexanderino]

So it's fine with gapless playback?

Yes. I've performed repeated tests with gapless tracks. No issues at all. However, the start (< 1 second) of the first track played is lost/faded in. That does not occur in the non-exclusive modes.

It's not fading, but muting for around 1/2 second to avoid pop sound during sample rate or PCM/DSD format changing, if there's no change, there's no muting, so it is a feature, and basically every dac dongle on the market does that, because most consumers will complain if there's a pop sound, it's actually a desired feature for most people.

Thank you for explaining it better than I did.

 

[Hifihedgehog]

Out of curiosity, did you give FlexASIO a try?

GitHub - dechamps/FlexASIO: A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME.

A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME. - dechamps/FlexASIO

github.com

GitHub - flipswitchingmonkey/FlexASIO_GUI: Simple configuration GUI for FlexASIO

Simple configuration GUI for FlexASIO. Contribute to flipswitchingmonkey/FlexASIO_GUI development by creating an account on GitHub.

github.com

It's a more configurable version of ASIO4All basically, and when configured to use WMD-KS internally, has served me very well WRT stability and transparency.

Interesting. Do you happen to know what the root cause of noise generation with ASIO4All is?

 

[GeekyBastard]

So it's fine with gapless playback?

Of course, there's no muting if there's no sample rate changes.

 

[GeekyBastard]

Yes. I've performed repeated tests with gapless tracks. No issues at all. However, the start (< 1 second) of the first track played is lost/faded in. That does not occur in the non-exclusive modes.


Thank you for explaining it better than I did.

If you use Foobar2000 as daily driver, there's a plugin called PreGap which could solve the muting "problem", it would add a silent part before the actual music starts, giving the dac some time to change its sample rate without messing with gapless playback. This kind of function was already built in other softwares like JRiver. @Labjr @alexanderino

 

[Eddie]

Of course, there's no muting if there's no sample rate changes.

This confuses me again.
Are your tests performed in WASAPI exclusive mode? This is the specific use case I referred to.

alexanderino originally writes:

When I start/stop after a few seconds, there is a fade-in/fade-out. Other than that, correct.

In summary: he writes that there is a fade-in when starting a track, a fade-out when stopping a track and both when searching within a track.
He also writes:

However, the start (< 1 second) of the first track played is lost/faded in. That does not occur in the non-exclusive modes.

The word "lost" makes me cringe. This reminds me of the Tanchjim SPACE, which skips the beginning of a track that has been started.

On the contrary, you write:

It's not fading, but muting for around 1/2~1 second to avoid pop sound during sample rate or PCM/DSD format changing, if there's no change, there's no muting

Now I would really like to know what's really going on. Unless I misunderstood both of you (which may be the case), who is right and who is wrong?

To summarize, in WASAPI exclusive mode (and in ASIO mode, too) with PCM and a constant sample rate (e.g. 96kHz) I don't want the following behavior:
• when starting a track: pops, clicks, fade-in, skip
• when stopping a track: pops, clicks, fade-out
• when searching within a track: pops, clicks, fade-out, fade-in

Can you, alexanderino or someone else please clarify this issue?

 

[Eddie]

Unfortunately I don't have a way to do that. The ASIO emulation adds that noise in this class of device and I need to use it to perform sweeps.

Out of curiosity: are you using the latest version of ASIO4ALL? It's 2.16 released on June 26.

In the change log the developer writes:
• Fixed regression that would sometimes constrain bit depth to 16 bits only.

Maybe this explains the 15dB jump in your THD+N vs. power sweeps.

 

[Eddie]

Out of curiosity, did you give FlexASIO a try?

GitHub - dechamps/FlexASIO: A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME.

A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME. - dechamps/FlexASIO

github.com

GitHub - flipswitchingmonkey/FlexASIO_GUI: Simple configuration GUI for FlexASIO

Simple configuration GUI for FlexASIO. Contribute to flipswitchingmonkey/FlexASIO_GUI development by creating an account on GitHub.

github.com

It's a more configurable version of ASIO4All basically, and when configured to use WMD-KS internally, has served me very well WRT stability and transparency.

For bit-perfect audio one should consider this: https://github.com/dechamps/FlexASIO/blob/master/FAQ.md#how-to-achieve-bit-perfect-audio-streaming
Otherwise, you may not get what you expect from ASIO.

A typical bit-perfect configuration uses WASAPI exclusive mode.

The old Kernel Streaming (WDM-KS) programming is still possible, but unlike WASAPI, it requires kernel mode, not user mode. It's much more dangerous (e.g. BSOD) than WASAPI if not implemented properly by the programmer.
This is one of the reasons why Microsoft developed WASAPI.

 

[alexanderino]

If you use Foobar2000 as daily driver, there's a plugin called PreGap which could solve the muting "problem", it would add a silent part before the actual music starts, giving the dac some time to change its sample rate without messing with gapless playback. This kind of function was already built in other softwares like JRiver. @Labjr @alexanderino

Sadly, foo_dsp_pregap didn't do the trick for me (irrespective of whether it was on the top or bottom of the DSP chain). However, adding silence before the first track in the playlist works. In foobar2000, use Ctrl+U (or File -> Add Location…) to add 1 second of silence and place it at the start, like this:

Voilà — no more issues in exclusive mode (as long as you don't pause, skip, or stop playback).

 

[alexanderino]

In summary: he writes that there is a fade-in when starting a track, a fade-out when stopping a track and both when searching within a track.

The fade-in when searching within a track is correct. However, I have corrected my previous post to:

When I start/un-pause/stop after a few seconds, there is a fade-in/fade-out. Other than that, correct.

To summarize, in WASAPI exclusive mode (and in ASIO mode, too) with PCM (any bit depth, any sample rate) I don't want the following behavior:
• when starting a track: pops, clicks, fade-in, skip
• when stopping a track: pops, clicks, fade-out
• when searching within a track: pops, clicks, fade-out, fade-in

I can clarify based on my experience, which is only WASAPI exclusive and PCM:

• when starting a track: fade-in (which means the start is trimmed off)
• when stopping a track: nothing
• when searching within a track: fade-in

 

[Eddie]

I can clarify based on my experience, which is only WASAPI exclusive and PCM:

• when starting a track: fade-in (which means the start is trimmed off)
• when stopping a track: nothing
• when searching within a track: fade-in

Thanks again for your updated information.
Fade-in or trim when starting is the exact same behavior as Tanchjim SPACE and Moondrop Dawn Pro. It's a disgrace.

Do I really have to buy a DAC/Amp for a few hundred Euros in order to get the desired behavior?
I mean, starting a track without fading in or trimming is a very basic and simple demand. I don't understand why some companies don't comply with this. Is it really that difficult to implement?

 

[GeekyBastard]

Sadly, foo_dsp_pregap didn't do the trick for me (irrespective of whether it was on the top or bottom of the DSP chain)

You'll need to set up the plugin correctly, maybe change the settings to this and test again? It works for me flawlessly (Not in DSD mode though, PreGap plugin doesn't work with DSD.)

@Labjr @Eddie I've already tested it in WASAPI exclusive mode, when combined with PreGap plugin with correct settings, it works flawlessly, no fade-in/out at start, no pop, no click, no skip.

If you don't want ANY cross-fade while seeking, disable the option in the second pic.

(It sounds choppy while seeking after disabling it, I personally leave it enabled, if you want to change some behaviors of it, just select and move the slider.)